表面拉曼增强光谱(SERS)技术 课件.ppt

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1、,表面拉曼增强光谱（SERS）技术,2014.3.24,主要内容,2. 研究热点,1. 基本原理,3. 自己工作,1. 基本原理,1928 年，印度科学家C.V Raman in首先在CCL4光谱中发现了当光与分子相互作用后，一部分光的波长会发生改变（颜色发生变化），通过对于这些颜色发生变化的散射光的研究，可以得到分子结构的信息，因此这种效应命名为Raman效应。,Provided by Prof. D. Mukherjee, Director of Indian Association for the Cultivation of Science,laser,scatter laser,瑞利

2、散射,scatter= laser,拉曼散射,弹性散射：频率不发生改变，如瑞利散射非弹性散射：频率发生改变，如拉曼散射,scatter laser,拉曼散射,能级示意图,虚态,电子基态,电子激发态,能量差,发射光子能量,7,2130 cm-1 n as, C-N,190 cm-1 as, Ag-N n s, Ag-Ag,2022/12/10,8,2153 cm-1 n as, C-N,196 cm-1 n as, S-Ag r i.p. S-C-N,1.1 Raman与SERS,1928 年，C.V RamanCCl4光谱,1974年 Fleischmann 等人粗糙化银电极吡啶分子,1977

3、年，Van Duyne和Creighton粗糙表面相关的表面增强效应,表面增强拉曼光谱（SERS）的特点,信息量大,灵敏度高,操作简便,谱图包含大量的化学信息，可反映结构信息，化学组成和环境信息,通过增强吸附和形成热点可实现痕量组分分析甚至单分子检测,无需复杂前处理，可直接原位监测，测试方便快捷,1.1 Raman与SERS,表面等离子体激元共振( Surface Plasmon resonance, SPR)引起的局域电磁场增强 由于Cu, Ag和Au 3种币族金属的d电子和s电子的能隙和过渡金属相比较大, 使得它们不易发生带间跃迁。只要对这3种金属体系选择合适的激发光波长, 便可避免因发生

4、带间跃迁而将吸收光的能量转化为热等, 从而趋向于实现高效SPR散射过程。避雷针效应 由于尖端效应，相对电荷密度高,电磁增强（EM enhancement）,1.1 Raman与SERS,106-1010 倍 SERS效应的主要来源,1.1 Raman与SERS,电磁增强（EM enhancement）影响因素,材料种类粒子形貌相对位置,Thomas, R. and R. Swathi (2012). The Journal of Physical Chemistry C 116(41): 21982-21991.,Fig Illustration of three types of chemi

5、cal enhancement mechanism s in comparison with free pyridine( Py) ( A) , chemical-bonding( CB) enhancement( B) , surface complexes( SC) enhancement( C) ,and photon-induced charge-transfer( PICT) enhancement (D),化学增强（CM enhancement）,1.1 Raman与SERS,10-102 倍 SERS效应,当分子化学吸附于基底表面时, 表面、表面吸附原子和其它共吸附物种等都可能与

6、分子有一定的化学作用， 这些因素对分子的电子密度分布有直接的影响，即对体系极化率的变化影响其Raman强度。 化学增强主要包括以下3类机理：由于吸附物和金属基底的化学成键导致非共振增强；由于吸附分子和表面吸附原子形成表面络合物(新分子体系)而导致的共振增强；激发光对分子-金属体系的光诱导电荷转移的类共振增强。,化学增强（CM enhancement）,1.1 Raman与SERS,1.1 Raman与SERS,化学增强（CM enhancement）影响因素,目标分子与探针的作用能级匹配激光波长，能量吸光性能与波长选择,杂原子，特殊官能团；石墨烯电荷转移，光吸收，光漂白共振增强，荧光,物理增强

7、（强） LSPR: 入射光频率与自由电子的振荡频率一致 选择性共振吸收；局部场大幅增强化学增强（弱）电荷转移；共振增强 荧光：Raman散射截面积10-30-10-25 cm2/分子，比荧光低10-15。而荧光常伴随Raman信号一起出现化学增强弱，但是引发荧光会产生很强的干扰，掩盖Raman信号选择基底及激光时，一方面调节贵金属吸收，同时根据目标分子结构进行调整，两者缺一不可,选择激发波长避开荧光干扰,532,633,785,Wavelength (nm),532 nm laser633 nm laser785 nm laser,激光器,样品,瑞利滤光片,共聚焦针孔,光栅,CCD,干涉滤光片

8、,狭缝,功率衰减片,显微镜,蓝：偏振片,拉曼光谱仪原理图,共焦针孔,物镜,共聚焦原理,位于焦点处的信号恰好汇聚在共聚焦针孔处，全部通过共聚焦针孔。位于焦点之外的信号汇聚在共聚焦针孔以外，只有极少部分可以通过共聚焦孔。,共焦拉曼的优势: 极大的提高了纵向分辨率 (2 m) 得到更好的横向分辨率 (1m) 有效地减少荧光干扰,共聚焦原理（真正针孔共焦）,Laser focus waist diameter,1.2 仪器与测试方法,Thermo Scientific DXR Raman Microscope,激光光源,滤光片,光栅,控制系统,载物台,显微系统,Raman,等离子体共振效应,SERS,

9、表面增强拉曼光谱（SERS）应用,激光光源,空气污染物监测,Nature Communications, 2013, 4, 1636,环境毒物监测,Nature Letters, 2010, 464, 392,反应机理研究,Nano Letters, 2013, 13, 5985,吸附模型研究,JPCC, 2013, 117, 22834,Anal. Chem, 2013, 85, 2223,生化测定及成像研究,欧莱雅产品在头发中的穿透深度,化妆品,2. 研究热点,2.1.1 基底制备-零维基底,不同形貌：球形，立方体，纳米片，三角锥不同大小：几十到几百纳米不同组成：单金属，多金属，半导体贵金

10、属,布朗运动：信号不稳定不规则团聚：信号不均匀,不足,大小结构：减弱运动固定化：信号均匀,解决方案,2.1.2 基底制备-一维基底,纳米线，纳米棒，纳米排列,特点：局部hot spot, 高的EF 制备困难，均匀性有限,Journal of the American Chemical Society. Just Accepted,2.1.3 基底制备-二维基底,气相沉积，平版印刷，刻蚀 top-down纳米组装（Langmuir-Blodgett) bottom-up,信号均匀，易于规模化但一般要特殊的设备,CxNy平面结构作为二维模板特殊结构增强EM和CM,Physical Chemistr

11、y Chemical Physics 16(6): 2224-2239.,Phys. Chem. Chem. Phys.,2013,15, 5288-5300,2.1.4 基底制备-三维基底,Advanced Functional Materials 22(1): 218-224.,ACS applied materials & interfaces. Just accepted.,有效体积三维热点利于吸附,Fabricated using equipment and reagents commonly found in chemistry laboratories.Minimal train

12、ing or experience required for fabrication.Easily transported to or fabricated at the point of sampling.Easily integrated into analytical systems. -Betz, J. F., et al. (2014). Simple SERS substrates: powerful, portable, and full of potential. Physical Chemistry Chemical Physics 16(6): 2224-2239.,基底制

13、备四原则,2.2 发展方向-实际应用,2.2.1 快速检测 痕量分析,Adv. Mater. 2013, 25, 35543559,ACS Nano, 2009, 3, 23292339.,2.2.2 免疫识别,Nano Lett., 2007,7, 28192823.,2.2.3 理化指标检测,温度，离子强度，pH等,Nat. Biotechnol., 2008, 26, 8390.,2.2.4 生物成像 临床诊断,特殊组织，细胞，癌细胞成像药物释放监测，药理研究,实验结合计算进行理论研究高效基底制备联用技术（HPLC-SERS, TLC-SERS）简便测试方法（便携式拉曼，在线监测)实际应

14、用（环境污染物，食品添加剂）生物成像,热点及发展趋势,我们的方向,简单的方法制备高效基底应用于环境污染物或食品添加剂的检测揭示其化学本质,反馈,Related work in our lab,Dependence of electronic structure of g-C3N4 on the layer number of its nanosheets: A study by Raman spectroscopy coupled with first-principles calculationsNovel One-pot Fabrication of Lab-on-a-BubbleAg S

15、ubstrate without Coupling-agent for Surface Enhanced Raman ScatteringMicro/nano-structured graphitic carbon nitride-Ag nanoparticle hybrids as new SERS substratesThree-Dimensional Plasmonic Hydrogel Architecture: Facile Synthesis and Its Macro Scale Effective SpaceA surface-enhanced Raman scattering

16、 method for detection of trace glutathione on the basis of immobilized silver nanoparticles and crystal violet probe,Dependence of electronic structure of g-C3N4 on the layer number of its nanosheets: A study by Raman spectroscopy coupled with first-principles calculations,Jizhou Jiang, Lei Ou-yang,

17、 Lihua Zhu, Anmin Zheng, Jing Zou, Xianfeng Yi， Heqing Tang, Carbon, 2014,80, 213221.,Figure S3 Schematic illustration of concentrated-H2SO4 intercalation-exfoliation process from coplanar bulk g-h-heptazine-C3N4 to ultrathin layers.,制备不同层数的氮化碳,42,三聚氰胺,多层氮化碳 (g-C3N4),剥离,1、2、4层氮化碳,44,单层和多层的Raman图谱区别,

18、两组峰的比值随层数的变化规律,峰位移与层数的变化规律,Novel One-pot Fabrication of Lab-on-a-BubbleAg Substrate without Coupling-agent for Surface Enhanced Raman Scattering,Jizhou Jiang, Lei Ou-Yang, Lihua Zhu, Jing Zou, Heqing Tang. Scientific reports, 2014 (4). 3942,静电吸附原位还原,a 2.510-6 mol L-1 CVb 粉末 CVc SiO2Ag+2.510-6mol L-1

19、 CV,灵敏度,结晶紫（CV）,增强因子,SERS 增强因子= 6.9108,批次重现性 RSD=9.6%基底稳定性 RSD=6.2%,重现性及稳定性,线性及检出限,线性范围2.510-8-2.510-6 mol L-1检出限 2.510-10 mol L-1,Submitted to Journal of Material Chemistry A,Micro/nano-structured graphitic carbon nitride-Ag nanoparticle hybrids as new SERS substrates,Three-Dimensional Plasmonic Hy

20、drogel Architecture: Facile Synthesis and Its Macro Scale Effective Space,Submitted to RSC Advances,Scheme 1 Preparation procedure of PVA-Ag hydrogel 3D substrate by an in situ reduction strategy.,Figure S4 Homogeneity and reproducibility of 15%PVA-1Ag. (a) SERS intensity distribution map of 15%PVA-

21、1Ag slice with a thickness of 100 m and (b) 200m (c) The SERS spectra of 2.510-6 mol L-1CV obtained at 10 spots randomly chosen from 15%PVA-1Ag. (d) SERS intensity at the 1620 cm-1 peak with 5 batches of 2.510-6 mol L-1CV captured 15%PVA-1Ag.,Figure 2. Raman mapping images of 2.510-6 mol L-1 CV-capt

22、ured 15%PVA-xAg using the intensity of the 1620 cm-1 band. a white light image of the sample area,Reproducibility,Good homogeneity across the entire substrate area;Good reproducibility with different batches.,Figure 3. Raman depth-scanning image of 2.510-6 mol L-1 CV-captured 15%PVA-xAg using the in

23、tensity of the 1620 cm-1 band. a 15%PVA-1Ag b 15%PVA-1.5Ag; c 15%PVA-2Ag; d 15%PVA-3Ag; e 15%PVA-5Ag; f Active depth of 15%PVA-xAg with different Ag+ concentration, respectively.,Active depth,15%PVA-1Ag 80 m;15%PVA-1.5Ag 120 m;15%PVA-2Ag 170 m; 15%PVA-3Ag 110 m; 15%PVA-5Ag 70 m.,spatial distribution

24、 of Raman intensity,Figure 4. SERS intensity of 2.510-6 mol L-1 CV captured by 15%PVA-xAg with different slice thicknesses at the 1620 cm-1 band. Black dots represent 15%PVA-1Ag and red dots represent 15%PVA-2Ag.,Active depth by slice,Fig. 8. (a) SERS spectra of CV captured substrates. CV and 4-ATP

25、concentration on PVA-2Ag hydrogel substrate.,Fig 9 Detection of 4-MBA using a portable Raman instrument,Trace detection,A surface-enhanced Raman scattering method for detection of trace glutathione on the basis of immobilized silver nanoparticles and crystal violet probe,竞争吸附 褪色效应 间接测定,非蛋白质硫源,氧化还原缓冲物质,低极化率,与Ag有强相互作用,谷胱甘肽（GSH）,a 1ppmCV,b Fe3O4Ag+1ppm CV c b +10mol L-1 GSH.,线性范围510-8710-7 mol L-1 检出限 410-8 mol L-1,线性及检出限,批次重现性 RSD=7.1%,重现性好,可控制备,方法稳定,重现性,